Inflammatory interstitial nephritis, either as a primary or secondary event, plays an essential role in the development of all forms of chronic renal failure. We have been studying this problem with an experimental model of immune-mediated interstitial nephritis in mice called anti-tubular basement membrane (alphaTBM-Ab/alpha3M-1-Ab) which are directed at a tubular target antigen (3M-1) expressed by the tubulointerstitium. Histologic damage occurs through the formation of interstitial mononuclear cell infiltrates that subsequently induce progressive fibrogenesis. The purpose of this grant is to evaluate the molecular parameters of the helper T cell repertoire producing the nephritogenic immune response, to further characterize the structural gene(s) encoding soluble T cell helper factor (ThF), and to analyze the connectivity of, and anti-idiotypic response to, the nephritogenic T and B cell repertoires by examining the molecular structure of a disease-modifying, cross-reactive idiotype (IdX). Our project will carefully examine the heterogeneity of helper T cells in susceptible and non-susceptible mice, the peptide recognition and preferred use of variable-region genes by their T cell receptors, the molecular structure of ThF, the cis-acting elements regulating the transcription of ThF, the effects of chimeric gene-deletion of ThF in transgenic mice, and the molecular structure of a highly conserved IdX determinant which can be used to modulate the expression of alphaTBM disease. The techniques of T cell cloning in culture, cDNA and genomic cloning, nucleotide sequencing, phosphorothioate-capped antisense oligonucleotide inhibition of protein translation in culture, eukaryotic protein expression through transfected shuttle vectors, homologous recombination producing gene-deleted mice, linkage of cis-acting gene fragments to reporter gene constructs, and peptide directed therapy of interstitial nephritis will be collectively utilized to address selected issues regarding the role of this T cell help and idiotypy in interstitial nephritis. We believe these studies, on balance, will provide new and useful information regarding the expression and control of autoimmune events central to the pathophysiology of progressive renal injury. It is our belief that such information may eventually be employed in therapeutic strategies which might favorably alter the natural history of immune-mediated interstitial nephritis.